In a wireless communication system, in order to determine a MCS for downlink transmission by a base station, a UE is required to estimate a Signal to Interference and Noise Ratio (SINR) of a received signal, determine to feed back a Channel Quality Indicator (CQI), and feed back the CQI via an uplink resource to the base station. Then, the base station determines a MCS for downlink transmission according to the received CQI. This is called a CQI feedback procedure. The above-described way of determining a MCS is applied for the scenario of single-user transmission.